In 2013, a mysterious man arrived in Erinsborough, claiming to be Sonya Rebecchi's long-lost Uncle Walter. As he won her
over, and also began a romance with neighbour Sheila Canning, it was revealed that he was actually an impostor, and had met the real Walter, an alcoholic, at a halfway house and had attempted to make
some money by stealing his identity. The impostor, whose real name was Dave, was sent packing, but three years later, Sonya's husband Toadie heard that the real Walter was trying to get in touch.
Knowing the strain that Sonya was under, Toadie gave him $5000 to get himself into rehab, worried that having her alcoholic uncle in the house might trigger a relapse for Sonya, a former addict herself. He then sent his brother
Stonie up to Newcastle to check on Walter, only to find that his house was abandoned and that he was in the pub.
When Walter later turned up in Erinsborough, claiming to have been sober for three weeks, Toadie was determined to keep him away, and had to cancel a planned business trip to Canberra with Sonya. When Walter then arrived at the
Rebecchi house, Toadie's friend Steph offered him a room at the motel she co-owned, and Toadie was disgusted to learn that Walter hadn't used the money for rehab, but was instead claiming that he'd
given it to a friend in need. With little reason to trust Walter, Toadie simply wanted him gone, and was alarmed when he returned the next day, just as Sonya made an early return from her trip. Toadie quickly covered, claiming that the
man was one of his clients named Mitch, and Sonya accepted this, though was a little perplexed by how over-friendly he was to her and her young daughter, Nell. When Sonya then bumped into Mitch again
at The Waterhole, he asked her, in her role as Erinsborough's Mayor, if there was a local charity he could approach about doing some volunteer work. As Toadie had painted Mitch as quite an unpleasant man, Sonya was a little reluctant at
first, but as he told her that he was trying to make up for past mistakes, something that resonated with her, she sat with him and talked through some charities. When she told him that she had to leave for an AA meeting, he asked to come
along, and Sonya was only too happy for him to join her.
Later that week, Walter attended another AA meeting with Sonya, where he also met Terese Willis, one of Sonya's friends and neighbours who'd also been having problems with alcohol for a number of months,
suffering a relapse after the death of her son, Josh. As Walter grew closer to both Sonya and Terese - and even went back to Terese's house and shared a kiss with her - Toadie was alarmed to learn that he
was still around, and decided that he had to tell a stunned Sonya the truth about Mitch's identity. At first, Sonya was unable to be around Walter, particularly after the ordeal she'd been through a few years earlier with the impostor, but
after speaking to Terese about how much she'd give to have Josh back in her life, Sonya agreed to see Walter again. As they were chatting about the past, Sonya was confused when Walter mentioned last seeing her parents when they were all
dressed up to go to a masquerade ball. Knowing that her parents rarely did things like that, and that they had been going to a ball on the night they died, she began to wonder if she could trust Walter. After managing to get hold of the
accident report, Sonya was shocked to realise that Walter had been in the car with them, and she demanded answers from him. Walter then admitted that he was actually her father - he'd had an affair with her mother Fiona, and Sonya was the
result. He told her that he'd been in the car that night trying to convince them to tell Sonya the truth about her parentage.
As Sonya realised that Walter was telling the truth, she felt a mixture of emotions - anger that he'd abandoned her and her younger sister Jade following the accident, but also happiness that she finally had
a parent in her life after so many years. As Walter dealt with the situation by falling off the wagon, Sonya took him home and they had a frank conversation, during which he admitted that he would give anything to be able to relive his life and
he a proper father to her. Sonya then agreed to help him deal with his alcohol problem, and he was grateful to be able to get to know Sonya and Nell, quickly proving himself to be a natural in the childcare department. As they grew closer, Sonya
invited Walter to stay with her and her family, and even left him alone with Nell for the day, though she did ask Sheila and Susan to call by and check that he was coping. When Sonya returned home that evening, she
found that Walter had successfully coped with Nell, and charmed Sheila and Susan, and she was beginning to think that her dad was too good to be true - until she spotted a text on his phone, from someone called Roxanne, asking if he'd told Sonya yet,
as they didn't have much time.
Sonya turned to Toadie, worried that they couldn't trust Walter, and Toadie explained that, when he'd first investigated Walter, he'd learnt that Roxanne was his ex-wife. He then tried to find out more, and learnt that Walter and Roxanne had a
14-year-old daughter named Zoe. Sonya then realised that she needed to get the full story, and confronted Walter, who explained that Zoe was dying from leukaemia and needed a bone marrow transplant. He told them that the money Toadie gave him had
actually gone towards Zoe's medical bills, and her illness was what had pushed him to finally get sober - though he also assured Sonya that he had been planning to get in touch with her for a long time, and he hadn't just contacted her in order to
help Zoe.
When Sonya agreed to have tests to see if she was a match, she finally met Zoe and the pair quickly hit it off, with scatty Zoe having a lot in common with her older half-sister. Sonya was impressed with the strength Zoe was showing, even as
Walter broke down in tears in front of her. Zoe referred to her cancer as 'Alfie' and did her best to keep her spirits up, though in a quiet moment with Sonya, she admitted that she just wanted it all to go away so that everyone could stop being
sad. When word came back that Sonya wasn't a match, Zoe reacted badly, having almost convinced herself that everything was going to be OK, and a heartbroken Walter then suggested that Nell could be tested - though Toadie was dead against it, Sonya went
ahead and had Nell tested anyway. When Zoe then fell ill and was admitted to Erinsborough Hospital, word came back that Nell was a match and Sonya was forced to tell Toadie what she'd done, but he was still against the idea of putting their young
daughter through the ordeal of being a donor. A desperate Walter then decided that he and Zoe would have to leave, asking if he could pick up Nell from daycare to say goodbye to her. When Zoe realised that her dad was intending to kidnap Nell, she
escaped at a gas station, taking Nell back to Ramsay Street with her. Walter wasn't far behind, and he quickly realised the stupidity of his actions, with Sonya only agreeing not to press criminal charges as it would hinder Zoe's chances of getting well.
Thankfully, the family finally received some good news when word came through from the USA that Sonya's son Callum, who'd initially been tested and rejected, was a match after all. Walter and Zoe then left for
California to begin treatment and although Sonya was happy to be saying goodbye to her new-found father and half-sister on such a positive note, her actions regarding Nell would have a negative impact on her marriage for a while to come.
In early 2018, Sonya heard that Zoe's cancer had returned, and that Walter wasn't coping well with the news and had suffered a relapse. Sonya and Nell went out to California to offer their support and a few weeks later reported back that
Zoe's treatment was going well and Walter had started attending his AA meetings again.
